Technical Field
The description relates to inductive (LC) sensors.
One or more embodiments may apply to LC sensors for use, e.g., in fluid metering applications, such as water and gas meters.
Description of the Related Art
Inductive sensing is based on an inductor-capacitor resonant circuit (which explains the current designation of “LC sensing”) which is pumped by an oscillator with the inductor acting as a sensing coil. As a conductive (e.g., metal) object comes in the vicinity of the coil, currents are generated in the object depending on various parameters such as, e.g., the material and dimensions of the object and/or the distance to the sensing coil. The currents thus generated form a magnetic field which reduces the oscillation amplitude of the resonant circuit (tank) thus changing the parallel resonance impedance of the circuit. Detecting/measuring such change may be exploited for various sensing purposes.
Inductive/LC sensing may be used in various industrial fields for, e.g., various types of contactless sensing of moving parts for various purposes such as detecting/measuring distance, speed or flow.
For instance, inductive/LC sensing is being increasingly applied, e.g., in water and gas meter applications with the possibility of offering power/efficient solution adapted to be directly embedded, e.g., in microcontroller units—MCUs.
In such a possible context of use, factors such as, e.g., reducing the number of (analog) components coupled with the sensor, facilitating digital processing of the sensing signals and simplifying control logic while providing reduced consumption may play a significant role.
Reducing the time involved in performing a certain measurement and/or the capability of handling multiple sensors represent a further factors of interest.
Time-based LC sensor excitation using, e.g., a high-speed (e.g., 4 MHz) clock source to control transfer of energy during excitation has been used with potential drawbacks represented, e.g., by power consumption and total measurement times in the range of, e.g., 50 microseconds.